It is estimated that at least about 42% of Americans between the ages of 52 and 64 and 73% of Americans between the ages of 65 and 74 get cataracts. A cataract is a clouding of the eye's lens that impairs a person's vision and, if left untreated, causes blindness. As a result, each year approximately 1.4 million people in the United States alone undergo cataract surgery, whereby the clouded lens is removed and replaced with an intraocular lens (IOL) implant.
A typical IOL includes an optic or lens body for focusing light toward the retina of the eye abd one or more fixation members or haptics extending outward from the optic for securing and centering the IOL in the desired position within the chamber of the eye. The IOL is implanted directly into the eye through a small incision in a way that reduces trauma and expedites post-surgery healing. To fit through this small incision, modern IOLs are designed to be deformed, e.g., rolled, folded or the like, to a relatively small profile and then allowed to return to their original shape within the eye.
A useful technique for inserting an IOL into the eye includes use of an IOL injector. Injectors for delivering IOLs into the eye typically employ a handpiece and a cartridge having a hollow, tapered insertion tube or cannula through which the folded IOL is passed using a push rod. The distal end of the cartridge insertion tube is beveled into a sharp point that enables insertion through the corneal incision and facilitates expulsion and manipulation of the IOL into the capsular bag. The cartridges are made of disposable materials, such as plastics, and remain in a sterile package until ready for coupling with the handpiece. Some injectors do without the cartridge, and may be reusable.
Conventional IOL cartridges include a load chamber connected to an injection tube. In many popular versions, such as in U.S. Pat. No. 4,681,102 to Bartell or U.S. Pat. No. 5,702,402 to Brady, the load chamber is formed by two hinged halves which receive the IOL, and which close to fold the IOL. A non-folding cartridge is seen in U.S. Pat. No. 5,474,562 to Orchowski in which forceps are used to insert the IOL into a proximal or rear opening of the cartridge. After mating the cartridge with the handpiece (if a separate cartridge is used), a push rod urges the IOL through the cartridge insertion tube into the eye. Typically, the load chamber is first partially filled with a liquid or gel, for example, a viscoelastic medium such as a sodium hyaluronate gel. The viscoelastic facilitates passage of the IOL through the injector, and in some cases the tip of the push rod does not directly contact the IOL, but instead engages the intermediate viscoelastic so as to distribute hydraulic pressure across the IOL and cause it to proceed through the injector and into the eye.
Some recent IOL injectors or cartridges are preloaded with an IOL to eliminate the steps associated with mating the IOL with the cartridge. Despite the reduction in complexity, preloaded injectors often require numerous steps to complete delivery, making it a difficult training challenge. Moreover, the syringe-style injector may be somewhat awkward to hold and the plunger advancement may be hard to control, leading to forceful ejections of the IOL, for example.
There remains a need for devices and methods that simplify the process of loading an IOL cartridge and provide improved control to the delivery system.